Not that Opeth's really technical death metal; it's a common misconception. I've seen albums like Blackwater Park labeled tech death when it's really plain ol' death or prog, thus I thought this might be the type of stuff you were referring to. To be honest I've seen the same shit with Dream Theater, which would be accurate except for the "death" part.
Obscura's good stuff, I mean, I consider them a damn good tech death band. I always lumped them in with bands like Cynic and Cryptopsy and the like, and Atheist and Death a notch above those. Cliche I know, but Focus and None So Vile are good albums. Decapitated's first album was really good to, but it's been a while since I listened to it. I consider Decapitated to be on the same level as, per say, Spawn of Possession (don't really know why, I just group bands together like this). Jupiter was a fine album, but it hasn't gone without competition for the past 17 years. But tech death is a genre I've always had a harder time defining, so I might be a bit out of my element here. If you consider Meshuggah tech death, which could be argued and counter argued, they're high up there on my list.
But yeah, A Celebration of Guilt and Obscura (album) I'd say are better than Jupiter.
You are the master that makes the grass green.